222 W. Lake St. Bloomingdale 2400 Randall Rd. Carpentersville 630-529-9394 847-428-6767 Dealing with Black Walnut Toxicity The roots of the Black Walnut (Juglans nigra) and Butternut (Juglans cinerea) produce a substance known as juglone. If other plants are planted within the root zone of these trees, they may be weakened or killed within a few months by the juglone.. The toxic zone from a mature tree occurs within a 50'-80' radius from the trunk. The area impacted extends outward each year as a tree matures. Young trees two to eight feet tall can have a root diameter twice the height of the tree. What about leaves, mulch, and wood chips? Walnut leaves can be composted because the toxin breaks down when exposed to air, water, and bacteria. The toxic effect can be degraded in two to four weeks. In soil, breakdown may take up to two months. Sawdust mulch, fresh sawdust, or wood chips are not suggested for plants sensitive to juglone. However, composting of bark for a minimum of six months provides a safe mulch even for plants sensitive to juglone.

Perennials & Bulbs Hosta Hosta (cultivars of some species may do poorly) Iris sibirica Siberian Iris BOTANICAL NAME COMMON NAME Lobelia Cardinal Flower Ajuga reptans Bugleweed Monarda Beebalm Alcea rosea Hollyhock Muscari Grape Hyacinth Anemone Windfl ower Narcissus Daffodil Arisaema triphyllum Jack-in-the-Pulpit Oenothera Evening Primrose Asarum europeaeum European Ginger Osmunda cinnamomea Cinnamon Fern Aster Aster Phlox paniculata Garden phlox Astilbe Astilbe Polemonium reptans Jacob’s Ladder Athyrium Lady Fern Pulmonaria Lungwort Campanula latifolia Bellfl ower Rudbeckia Black-eyed Susan Chrysanthemum Mum Sanguinaria canadensis Bloodroot Crocus Crocus Scilla sibirica Siberian Squill Dicentra Bleeding Heart Sedum Stone-crop Dryopteris Wood Ferns Stachys byzantina Lamb’s Ear Eupatorium Joe-Pye Weed Tradescantia virginica Spiderwort Galium odoratum Sweet Woodruff Trillium Wood Lily Salanthus nivalis Snow Drop Veronica Speedwell Geranium sanguineum Bloody Crane's-bill Viola Violets Helianthus Perennial Sunfl ower Hemerocallis Daylily Heuchera Coralbell

Ask us! We are here to answer all your gardening questions. 222 W. Lake St. Bloomingdale 2400 Randall Rd. Carpentersville 630-529-9394 847-428-6767 Dealing with Black Walnut Shrubs Trees BOTANICAL NAME COMMON NAME BOTANICAL NAME COMMON NAME Berberis thunbergii Barberry Acer palmatum Japanese Maple Euonymus alatus Burning Bush Acer rubrum Red Maple Forsythia intermedia Forsythia Acer saccharum Sugar Maple Hamamelis Witch-Hazel Amelanchier Serviceberry Hibiscus syriacus Rose of Sharon Betula nigra River Birch Hydrangea arborescens Annabelle Hydrangea Carpinus caroliniana American Hornbeam Hypericum St. John’s Wort Cercis canadensis Redbud Juniperus Juniper Chionanthus virginicus Fringetree Philadelphus Mock Orange Cornus alternifolia Pagoda Dogwood Physocarpus opulifolius Ninebark Gleditsia triacanthos Honeylocust Ribes alpinum Alpine Currant Liriodendron tulipifera Tulip Tree Thuja occidentalis Arborvitae Morus alba Mulberry Viburnum carlesii Koreanspice Viburnum Quercus rubra Red Oak Viburnum dentatum Arrowwood Viburnum Salix Willow Yucca fi limentosa Yucca Tsuga Hemlock

These lists are by no means comprehensive, nor guaranteed. Much of the information was informally acquired. Some parts of this brochure were adapted from the Ohio State University Extension Fact sheet HYG-1148-93.

Ask us! We are here to answer all your gardening questions.